The renovation of Quincy’s Old City Hall is expected to start this month, launching a transformation designed to bring the building back to its roots.

“It’s going to be terrific,” said James Edwards, an architect working on the building and president of the Quincy Historical Society. “It’s been over 100 years, no real significant work has been done on that building. It’s past its time and it’s a city treasure.”

Water splotches on the ivory-colored ceiling are telltale signs of a leaky roof, and the water problems continue all the way down into the basement. The vents in the City Council chambers blasted air cold enough to refrigerate meat, and a lack of sprinklers was just one of the building’s numerous code violations.

On the second floor, the once-sprawling Great Hall had been chopped into smaller spaces, and the shutters that adorned the windows have long vanished.

The shortcomings will be corrected and the past grandeur restored with more than $8 million in renovations, which will be performed by Nauset Construction Corp. The Needham-based company was awarded the contract in August.

“I’m excited and nervous,” Edwards said. “This is a big job, and the eyes of the city are on this project.”

The restoration of Old City Hall will dovetail with work on the Adams Green, a park space that is designed to take over Hancock Street along the stretch of City Hall.

To begin underground utility work for the park, the area in front of New City Hall will be dug up. Bricks inlaid with names that currently provide the footing in the area will be set aside for another use. In the basement of Old City Hall, areas will be allocated for the utility controls and water pumps for the park.

Because Nauset will undertake some of the Adams Green Park work, bids for the project came in close to $9 million. However, roughly $1 million is attributable to Adams Green and will be paid with park funding.

City councilors previously approved spending $18 million to renovate both Old City Hall and the nearby Coddington Building. An annual appropriation of $550,000 from the city’s Community Preservation Committee fund will help repay the bond issued to finance the projects.

According to Mayor Thomas Koch, construction will begin within two weeks, and the work will be all-encompassing.

“There are a lot of infrastructure issues — mechanical, structural, not only leaking roofs and windows, water getting into the basement. All those things will be done, and the building will be brought up to code,” Koch said in an interview last week.

In addition to structural upgrades, the look of the interior will change drastically. The first floor will be opened up, and meeting rooms for municipal boards will have a more permanent home. Historic documents will be displayed in an exhibit space on the other side of the first floor.

The double-sided staircase will return to its former glory, leading to an expansive hall that recalls the past.

“You lost that beautiful space . . . the building was carved up to council chambers for half [of what] that space was. The Great Hall will be the full width and length of the building,” Koch said.

“For public events, it will be terrific. The council will continue to be there. This was tight when you had major meetings or hearings . . . for a city of 93,000, 80 seats doesn’t cut it. You’ll have seating for 200.”

The basement will boast additional meeting space. Exits will be added for safety, and some features — such as a historic jail cell — will be restored.

Outside, the connection to the new City Hall will change, accommodating an elevator, extra stairwells, and QATV studios, and exposing the rough granite on the back of the building. New windows will accompany a new roof, and the long-gone shutters will be replicated and replaced.

“It certainly will be back to its original state and grandeur,” Koch said, and for the first time in decades, the vision of architect Solomon Willard will be seen with present-day eyes.

Even with so much to do, Koch said, he expects the project to be completed by next fall.

“I’m surprised they will be able to accomplish it as fast as they say,” said City Councilor Brian McNamee. “I’m very, very glad the mayor has chosen this property as well as Coddington to be renovated and preserved. They are worthy of the investment, the preservation.”

For Quincy Historical Society executive director Ed Fitzgerald, the significance of the renovation of Old City Hall is as symbolic as it is tangible.

Built with local granite and originally paid for by Quincy residents, the historic building will be “a testament to democracy,” he said.

“The citizens of the town raised the money to pay for that [building] themselves,” Fitzgerald said. “This wasn’t . . . a gift. It was paid for by the people of Quincy, and I’m really looking forward to seeing what the inside will be like.”

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